In the machining process of an automobile hub, the central hole of the hub needs to be clamped by a tensioning device. At present, most tensioning devices are driven by motors or hydraulic pressure. The tensioning devices driven by motors need deceleration mechanisms, and some even need brakes, so that the whole tensioning devices are too large, too high in cost and inconvenient to operate. The tensioning devices driven by hydraulic pressure need dedicated hydraulic valves, hydraulic pumps and complete hydraulic loops, so the costs are higher. Besides, the traditional electric or hydraulic driven tensioning mechanisms consume considerable electric energy.
In some small-scale machining or hub repair occasions, some tensioning devices which are small, convenient to operate and low in energy consumption are urgently needed.